Method for eliminating redundant method calls in an object oriented program

ABSTRACT

A method and machine-readable medium provide flags to commonly derived objects so that redundant method calls are avoided.

FIELD OF INVENTION

[0001] The present invention relates to object oriented programming, and more specifically to efficient performance of processes repeated in related objects.

BACKGROUND OF THE INVENTION

[0002] Embodiments of the present invention are discussed in the context of Java class library performance because that is a very popular form of object-oriented programming at the present time because it is applicant to forms of object-oriented programming. Like most object-oriented programming paradigms (OOPs) objects and methods are implemented to be self-contained. Therefore, when a second object is derived from a first object, and a third object is derived from a second object, as in the case of a Java string class and its parent classes, a process may be included in the subclasses which duplicates a function in the object in the parent class.

[0003] One example of such an operation is a function to check for a buffer overflow during execution. Normally, if a buffer will not overflow during execution of a subclass, it will not overflow during execution of the parent class (unless the buffer is explicitly modified). However, assuming a method of a derivative object uses a buffer to hold a context of a stream, the object will check buffer capacity before passing execution to the next higher level object. Consequently, excessive, redundant method calls will be inherent in Java class libraries. The excessive calls decrease Java performance and increase overhead. When data shows that excessive redundant method execution can degrade the performance of certain Java class library method calls by two times.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Embodiments of the invention are described by way of exemplification in the following description taken in connection with the following drawings:

[0005] Of the drawings:

[0006]FIG. 1 is a block diagram illustrating operation of an object and parent objects within a Java application and further illustrating the position of a flag to each object field;

[0007]FIG. 2 is a block diagram illustrating operation of the embodiment of FIG. 1;

[0008]FIG. 3 is a Java code statement illustrative of a further embodiment of the present invention; and

[0009]FIG. 4 is an flow chart of the operation of the embodiment of FIG. 3. of a method for dealing the check until as late as possible.

DETAILED DESCRIPTION OF THE INVENTION

[0010]FIG. 1 is a block diagram of a Java application 10 through a Java application program interface (API) 14 a second derivative object (AAA) 16 is derived from a first derivative object AA 18 which in turn is derived from a first object A 20. The object AAA 16 and its parent classes will have methods in common. In this particular example, one of the methods of object AAA 16 uses a buffer to hold the contents of a string. In order to make proper use of the buffer, object AAA 16 checks buffer capacity before passing execution to object AA 18. Object AA 18 performs the same function before passing execution to object A 20 within its parent class. Object A 20 being the parent of AA 18, contains the same Ensure Capacity( ) procedure. Objects AAA 16, AA 18 and A 20 comprise sequences of objects derived from a common source library.

[0011] It is desirable to eliminate the redundant method call inherited from a parent class. In this particular example, the redundant process is checking buffer capacity, but the invention is applicable to eliminating other redundant processes called by related objects as well. In the absence of a method in which the buffer is going to be modified, check of buffer capacity for the execution of the method on the related objects need be performed only once.

[0012] In order to inform the system of when the potentially redundant method calls are or are not necessary, information is provided. In one form of this implementation, the object AAA 16 is tagged with a define flag 24 and the object A 20 is tagged with a use flag 28. The object AA 18 may be tagged with a use flag 26. This operation is described with respect to FIG. 2, which is a flow chart. At block 40, the Java API 14 examines each successive related object, here example 5 by the objects 16, 18 and 20. At block 42, the API examines whether the object's flag indicates that a buffer check has been performed. If not, at block 44, the buffer check is performed. In this manner, redundant calls are prevented. FIG. 3 is an illustration on a further manner of eliminating redundant “ensure capacity” calls which is transparent to operation. FIG. 3 is a block of Java code illustrating a provision of the following constraints.

[0013] For each object, a pair of “root and leaf” flags is defined. The root flag is placed at the Java API entry point or in the last object that modifies the buffer. The leaf flag is placed at the leaf function that performs the last redundant check. During the execution of the API 14 to objects 16, 18 and 20 the redundant check is disabled at all objects except the leaf. The check is delayed until as late as possible. If an exception is established at the leaf, the actual signaling will happen at the root.

[0014] In the method as illustrated in FIG. 1, the root flag will be placed in object AAA 16 if object AA 18 does not modify the buffer. The root flag will be placed in object AA 18 if the buffer will be modified. A leaf flag is placed in object A 20. Checks are disabled at object AA 18 and AAA 16 but not object A 20. If an exception is raised during the execution of “ensure capacity” call (in object A 20, the exception will be recorded to have happened in object AAA 16.) The implementation of this technique is illustrated in FIG. 3 which represents code therefore. The program at line 2, determines if an object is a java application program interface. In this case the object modifies shared data at line 3 of the code, the object attribute will be labeled as a root. If the object is not a Java API, then the object attribute is labeled as a leaf, as seen at the end of line 4. As seen at line 7, if the object catches an exception to the buffer capacity, the exception underscore caught value is set to one. At lines 9 and 10, if the exception is caught, the objection is attributed to the root.

[0015]FIG. 4 is a flowchart illustrating the using of root/leaf pair inserted in class libraries. Block 60, at block 62, the flag is checked. Block 64 determines whether the flag is a root flag or a leaf flag. In the case of root flag, the performed method is not called and operation proceeds. In the case of a leaf flag, at block 66 the called method is performed and operation proceeds. In this embodiment using the illustration of FIG. 4, the flag 24 is the root flag, and the flag 28 is the leaf flag.

[0016] The present invention also comprises a machine-readable medium as a method. A machine-readable medium includes any mechanism that provides (i.e., stores and/or transmits information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium includes read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage medial; flash memory devices; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.) and the like.

[0017] The invention is also used to construct efficient Java class libraries and enable increased performance. The above specification has been written with a view toward enabling those skilled in the art to make many departures from specific examples illustrated herein to produce the method and processor constructed in accordance with the present invention. 

What is claimed is:
 1. A method comprising processing a plurality of objects based on a single Java class library, each said object comprising a method call, calling for an operation that is redundantly performed for all objects in the group of objects; and providing a first flag in a pre-selected sequence of the object for permitting the operation call and a second flag in another object at another position in the sequence of objects for disabling the method call.
 2. The method according to claim 1, wherein said objects include a Java string class object and objects from parent classes of said object.
 3. The method according to claim 2 wherein providing a first flag comprises providing a “define” flag, and providing said second flag comprises providing a “use” flag, said first flag being provided in a first of said objects in sequence to be processed and said second flag in a last object in the sequence to be processed.
 4. The method according to claim 2 wherein providing said first flag and said second flag comprises providing a pair of root and leaf flags, said leaf set flag comprising the second flag and said root flag comprising the first flag, said root flag being placed at a first java API entrance point of said group of objects, and placing the leaf flag at the leaf function that performs the last same method call and disabling the redundant method call at all objects except the leaf.
 5. The method according to claim 4 wherein an exception is raised and further wherein said exception is reported as having happened at the object containing the root flag.
 6. The method according to claim 5 wherein the method comprises a check buffer method and wherein the flags indicate whether buffer capacity has been checked by a corresponding Java application.
 7. A machine-readable medium that provides instructions which, when executed by a processor, cause said processor to perform operations comprising a method call, calling for an operation that is redundant performed for all objects in the group of objects; and providing a first flag in a pre-selected sequence of the object for permitting the operation call and a second flag in another object at another position in the sequence of objects for disabling the method call.
 8. A machine-readable medium according to claim 7 that provides instructions which, when executed by a processor, cause said processor to perform operations wherein said objects include a Java string class object and objects from parent classes of said object.
 9. A machine-readable medium according to claim 8 that provides instructions which, when executed by a processor, a first flag comprising a “define” flag, and providing said second flag comprising a “use” flag, said first flag being provided in a first of said objects in sequence to be processed and said second flag in a last object in the sequence to be processed.
 10. A machine-readable medium according to claim 8 that provides instructions which, when executed by a processor, provides a pair of root and leaf flags comprising said first flag and said second flag, said leaf set flag comprising the second flag and said root flag comprising the first flag, said root flag being placed at a first Java API entrance point of said group of objects, and placing the leaf flag at the leaf function that performs the last same method call and disabling the redundant method call at all objects except the leaf.
 11. A machine-readable medium according to claim 10 that provides instructions which, when executed by a processor, when an exception is raised reporting said exception is as having happened at the object containing a root flag.
 12. A machine-readable medium according to claim 11 that provides instructions which, when executed by a processor, the method comprises a check buffer method and wherein the flags indicate whether buffer capacity has been checked by a corresponding Java application.
 13. A Java application program interface comprising processing a plurality of objects based on a single Java class library, each said object comprising a method call, calling for an operation that is redundantly performed for all objects in the group of objects; and providing a first flag in a pre-selected sequence of the object for permitting the operation call and a second flag in another object at another position in the sequence of objects for disabling the method call.
 14. The Java application program of claim 13 wherein said objects include a Java string class object and objects from parent classes of said object.
 15. The Java application program of claim 14 wherein the method comprises a check buffer method and wherein the flags indicate whether buffer capacity has been checked by a corresponding Java application. 